Test System with Test Trays and Automated Test Tray Handling

ABSTRACT

A test system may be provided in which devices under test (DUTs) are loaded into test trays. Test trays may be tested at test stations. Test trays may be moved between test stations using a conveyor belt system. Each test station may include test equipment for testing DUTs and automated loading equipment for latching incoming test trays moving along the conveyor belt. The automated loading equipment may include a first movable arm configured to pick up a test tray from the conveyor belt and a second movable arm. The first arm may hand off (transfer) the test tray to the second arm. The second arm may move the test tray towards associated test equipment for testing. Upon completion of testing, the second arm may drop off the test tray onto the conveyor belt. Multiple layers of test stations may be stacked on top of each other for improved test throughput.

This application claims the benefit of provisional patent application No. 61/595,572, filed Feb. 6, 2012, which is hereby incorporated by reference herein in its entirety.

BACKGROUND

This relates generally to automation, and more particularly, to automated equipment for use in manufacturing operations such as testing.

Electronic devices are often tested following assembly to ensure that device performance meets design specifications. For example, a device may be tested at a series of test stations to ensure that components and software in the device are operating satisfactorily. At each test station, an operator may couple a device to test equipment using a cable. Following successful testing at all test stations, a device may be shipped to an end user.

The process of attaching and detaching test cable connectors and the manual operations associated with performing tests at test stations can be cumbersome and burdensome to test system operators. If care is not taken, tests may be less accurate and more time consuming than desired.

It would therefore be desirable to be able to provide improved ways of performing manufacturing operations such as testing operations on electronic devices.

SUMMARY

A test system may be provided in which devices under test are loaded into test trays. Test trays in the test system may be tested at test stations. A conveyor belt may be used to move test trays from one test station to another. Each test station may include loading equipment and test equipment. The loading equipment at each test station may include first and second movable arms. The loading equipment may include computer-controlled motor-driven or air-driven positioners configured to move the first and second arms along at least three orthogonal axes.

The first arm may be configured to pick up a test tray from the conveyor belt (e.g., by mating arm engagement features with corresponding test tray engagement features). The first arm may hand off (or transfer) the test tray to the second arm (e.g., the second arm may receive the test tray from the first arm). The second arm may be move the test tray towards the test equipment for testing. For example, the test equipment may be used to test the function of one or more input/output circuitry in the device under test.

In one suitable arrangement, the test system may include at least two layers of test stations stacked on top of one another. As an example, a first layer of test stations may be stacked on top of a second layer of test stations. A first conveyor belt may be configured to convey devices under test past test stations in the first layer, whereas a second conveyor belt may be configured to convey devices under test past test stations in the second layer. Testing devices under test using this configuration may enhance test throughput.

Further features of the present invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an illustrative electronic device such as a handheld device of the type that may be manufactured using automated equipment in accordance with an embodiment of the present invention.

FIG. 2 is a schematic diagram of an illustrative electronic device with input/output devices and wireless communications circuitry in accordance with an embodiment of the present invention.

FIG. 3 is a diagram of manufacturing equipment of the type that may be used in manufacturing an electronic device in accordance with an embodiment of the present invention.

FIG. 4A is an exploded perspective view of an illustrative device under test, pad extender, and test tray in accordance with an embodiment of the present invention.

FIG. 4B is a perspective view of an illustrative device under test, pad extender, and test tray in accordance with an embodiment of the present invention.

FIG. 5A is a top perspective view of an illustrative test tray in accordance with an embodiment of the present invention.

FIG. 5B is a bottom perspective view of an illustrative test tray in accordance with an embodiment of the present invention.

FIG. 5C is a perspective view of an illustrative test tray in which a device under test has been mounted in accordance with an embodiment of the present invention.

FIG. 6 is a diagram of an illustrative test system with loading equipment and test equipment in accordance with an embodiment of the present invention.

FIG. 7 is a top view of a conveyor belt in a test system showing how a test tray on the conveyor belt may be picked up by a test station pick-up arm in accordance with an embodiment of the present invention.

FIG. 8 is a cross-sectional side view of a test station pick-up arm that has engaged a mating test tray in a test system in accordance with an embodiment of the present invention.

FIG. 9 is a side view showing different possible positions of a pick-up arm and a drop-off arm in a test station in accordance with an embodiment of the present invention.

FIG. 10 is a flow chart of illustrative steps involved in testing devices under test using a test system of the type shown in FIG. 6 in accordance with an embodiment of the present invention.

FIG. 11 is a diagram of a test system with multiple stacked layers of test stations in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION

Electronic devices such as electronic device 10 of FIG. 1 may be manufactured using automated manufacturing equipment. The automated manufacturing equipment may include equipment for assembling device components together to form an electronic device. The automated manufacturing equipment may also include testing systems for evaluating whether devices have been properly assembled and are functioning properly.

Devices such as device 10 of FIG. 1 may be assembled and tested using an automated manufacturing system. The manufacturing system may include one or more stations such as one or more test stations for performing testing operations.

Devices that are being tested in a test system may sometimes be referred to as devices under test (DUTs). Devices under test may be provided to the test stations using a conveyor belt, using robotic arms, or using other loading equipment.

Any suitable device may be tested using test equipment. As an example, device 10 of FIG. 1 may be tested. Device 10 may be a computer monitor with an integrated computer, a desktop computer, a television, a notebook computer, other portable electronic equipment such as a cellular telephone, a tablet computer, a media player, a wrist-watch device, a pendant device, an earpiece device, other compact portable devices, or other electronic equipment. In the configuration shown in FIG. 1, device 10 is a handheld electronic device such as a cellular telephone, media player, navigation system device, or gaming device.

As shown in FIG. 1, device 10 may include a housing such as housing 12. Housing 12, which may sometimes be referred to as a case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of these materials. In some situations, parts of housing 12 may be formed from dielectric or other low-conductivity material. In other situations, housing 12 or at least some of the structures that make up housing 12 may be formed from metal elements.

Device 10 may, if desired, have a display such as display 14. Display 14 may be a touch screen that incorporates capacitive touch electrodes or may be insensitive to touch. Display 14 may include image pixels formed from light-emitting diodes (LEDs), organic LEDs (OLEDs), plasma cells, electrophoretic display elements, electrowetting display elements, liquid crystal display (LCD) components, or other suitable image pixel structures. A cover glass layer may cover the surface of display 14. Openings for buttons such as button 20, openings for speaker ports such as speaker port 22, and other openings may be formed in the cover layer of display 14, if desired.

The central portion of display 14 (i.e., active region 16) may include active image pixel structures. The surrounding rectangular ring-shaped inactive region (region 18) may be devoid of active image pixel structures. If desired, the width of inactive region 18 may be minimized (e.g., to produce a borderless display).

Device 10 may include components such as front-facing camera 24. Camera 24 may be oriented to acquire images of a user during operation of device 10. Device 10 may include sensors in portion 26 of inactive region 18. These sensors may include, for example, an infrared-light-based proximity sensor that includes an infrared-light emitter and a corresponding light detector to emit and detect reflected light from nearby objects. The sensors in portion 26 may also include an ambient light sensor for detecting the amount of light that is in the ambient environment for device 10. Other types of sensors may be used in device 10 if desired. The example of FIG. 1 is merely illustrative.

Device 10 may include input-output ports such as port 28. Port 28 may include audio input-output ports, analog input-output ports, digital data input-output ports, or other ports.

Sensors such as the sensors associated with region 26 of FIG. 1, cameras such as camera 24, buttons such as button 20, and ports such as port 28 may be located on any suitable portion of device housing 12 (e.g., a front housing face such as a display cover glass portion, a rear housing face such as a rear planar housing wall, sidewall structures, etc.). For example, buttons such as button 21 may be located on a sidewall portion of housing 12.

A schematic diagram of an electronic device such as electronic device 10 is shown in FIG. 2. As shown in FIG. 2, electronic device 10 may include storage and processing circuitry 27. Storage and processing circuitry 27 may include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio codec chips, application specific integrated circuits, etc.

Storage and processing circuitry 27 may be used to run software on device 10, such as internet browsing applications, voice-over-internet-protocol (VoIP) telephone call applications, email applications, media playback applications, operating system functions, etc. To support interactions with external equipment, storage and processing circuitry 27 may be used in implementing communications protocols. Communications protocols that may be implemented using storage and processing circuitry 27 include internet protocols, wireless local area network (WLAN) protocols (e.g., IEEE 802.11 protocols—sometimes referred to as WiFi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol, cellular telephone protocols, etc.

Circuitry 27 may be configured to implement control algorithms that control the use of antennas in device 10. For example, to support antenna diversity schemes and MIMO schemes or beam forming or other multi-antenna schemes, circuitry 27 may perform signal quality monitoring operations, sensor monitoring operations, and other data gathering operations and may, in response to the gathered data, control which antenna structures within device 10 are being used to receive and process data. As an example, circuitry 27 may control which of two or more antennas is being used to receive incoming radio-frequency signals, may control which of two or more antennas is being used to transmit radio-frequency signals, may control the process of routing incoming data streams over two or more antennas in device 10 in parallel, etc.

Input/output circuitry 29 may be used to allow data to be supplied to device 10 and to allow data to be provided from device 10 to external devices. Input/output circuitry 29 may include input/output devices 31. Input/output devices 31 may include touch screens, displays without touch sensor capabilities, buttons, joysticks, click wheels, scrolling wheels, touch pads, key pads, keyboards, microphones, speakers, tone generators, vibrators, cameras, sensors, light-emitting diodes and other status indicators, light sources, audio jacks and other audio port components, data ports, light sensors, motion sensors (accelerometers), capacitance sensors, proximity sensors, etc. A user can control the operation of device 10 by supplying commands through input/output devices 31 and may receive status information and other output from device 10 using the output resources of input/output devices 31.

Wireless communications circuitry 33 may include radio-frequency (RF) transceiver circuitry formed from one or more integrated circuits, power amplifier circuitry, low-noise input amplifiers, passive RF components, one or more antennas, transmission lines, and other circuitry for handling RF wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications).

Wireless communications circuitry 33 may include satellite navigation system receiver circuitry 35, transceiver circuitry such as transceiver circuitry 37 and 39, and antenna circuitry such as antenna circuitry 41. Satellite navigation system receiver circuitry 35 may be used to support satellite navigation services such as United States' Global Positioning System (GPS) (e.g., for receiving satellite positioning signals at 1575 MHz) and/or other satellite navigation systems.

Transceiver circuitry 37 may handle 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications and may handle the 2.4 Bluetooth® communications band. Circuitry 37 may sometimes be referred to as wireless local area network (WLAN) transceiver circuitry (to support WiFi® communications) and Bluetooth® transceiver circuitry. Circuitry 33 may use cellular telephone transceiver circuitry (sometimes referred to as cellular radio) 39 for handling wireless communications in cellular telephone bands such as bands at 850 MHz, 900 MHz, 1800 MHz, 1900 MHz, and 2100 MHz or other cellular telephone bands of interest.

Examples of cellular telephone standards that may be supported by wireless circuitry 33 and device 10 include: the Global System for Mobile Communications (GSM) “2G” cellular telephone standard, the Evolution-Data Optimized (EVDO) cellular telephone standard, the “3G” Universal Mobile Telecommunications System (UMTS) cellular telephone standard, the “3G” Code Division Multiple Access 2000 (CDMA 2000) cellular telephone standard, and the “4G” Long Term Evolution (LTE) cellular telephone standard. Other cellular telephone standards may be used if desired. These cellular telephone standards are merely illustrative.

Wireless communications circuitry 33 may include circuitry for other short-range and long-range wireless links if desired. For example, wireless communications circuitry 33 may include wireless circuitry for receiving radio and television signals, paging circuits, etc. In WiFi® and Bluetooth® links and other short-range wireless links, wireless signals are typically used to convey data over tens of hundreds of feet. In cellular telephone links and other long-range links, wireless signals are typically used to convey data over thousands of feet or miles.

Wireless communications circuitry 33 may include one or more antennas 41. Antennas 41 may be formed using any suitable antenna type. For example, antennas 41 may include antennas with resonating elements that are formed from loop antenna structures, patch antenna structures, inverted-F antenna structures, slot antenna structures, planar inverted-F antenna structures, helical antenna structures, hybrids of these designs, etc. Different types of antennas may be used for different bands and combinations of bands. For example, one type of antenna may be used in forming a local wireless link antenna and another type of antenna may be used in forming a remote wireless link antenna.

FIG. 3 is a diagram of an illustrative system of the type that may be used for manufacturing operations such as device testing. As shown in FIG. 3, system 30 may include one or more stations such as test stations 36. In general, test system 30 may include automated equipment that is used in loading and unloading devices under test, in conveying devices under test between test stations, and in performing tests and maintaining a database of test results. Each test station 36 may, for example, include test equipment 44 for performing one or more tests on device under test 10 and may therefore sometimes be referred to as a device tester or DUT tester. For example, a first type of test station 36 may have equipment for testing a display in DUT 10. A second type of test station 36 may have equipment for testing an audio component in DUT 10. Yet another type of test station 36 may have equipment for testing light sensors in DUT 10. Yet another type of test station 36 may have equipment for testing wireless communications circuitry in DUT 10. If desired, test system 30 may include more than one test station of the same type arranged along conveyor belt 38 so that multiple DUTs 10 can be tested in parallel.

Device under test 10 may, if desired, be installed in a test tray such as tray 32. Tray 32 may be configured to receive one or more devices under test. For example, tray 32 may have multiple slots, each of which is configured to receive a corresponding device under test. If desired, tray 32 may be configured to receive only a single device under test.

Device 10 may be installed in test tray 32 manually or using automated equipment. To facilitate manual installation, test tray 32 may include features to facilitate human manipulation. For example, test tray 32 may include features that help an operator open and close clamps or other device holding features in test tray 32.

Device under test 10 that is mounted in test tray 32 may be conveyed between test stations 36 using a conveyor belt such as conveyor belt 38 (e.g., a belt that moves in direction 40). When using a conveyor system such as one or more conveyor belts 38, each test station 36 may be provided with loading mechanisms (or loader) 46. With this type of arrangement, test tray 32 may serve as an interface between DUT 10 and loader 46. Test tray 32 may, for example, be more robust than DUT 10, may have engagement features that are configured to mate with loader 46, may have an identification number that facilitates tracking, and may have other features that facilitate testing of DUT 10 by test stations 36.

For example, loader 46 in each test station 36 may be provided with one or more computer-controlled positioning arms. The positioning arms in loader 46 may be used in picking up a test tray (i.e., a test tray that is loaded with DUT 10) from conveyor 38 (see, arrow 50), may be used to present DUT 10 in the test tray to tester 44 at that test station to perform desired testing the DUT, and may be used to replace the test tray on conveyor 38 following testing (see, arrow 52).

Test stations 36 may provide test results to computing equipment such as test host 42 (e.g., one or more networked computers) for processing. Test host 42 may maintain a database of test results, may be used in sending test commands to test stations 36, may track individual trays and devices under test as the trays and devices pass through system 30, and may perform other control operations.

FIG. 4A is a diagram showing how device under test 10 may be received within test tray 32 and showing how test tray 32. As shown in FIG. 4A, test tray 32 may have sidewalls 100 that are configured to receive a device under test such as DUT 10. Device under test 10 may have one or more connector ports such as port 28 (see, e.g., FIG. 1). A pad extender such as pad extender 144 may have a mating connector such as plug 146. Plug 146 may be configured to mate with a connector in port 28 when DUT 10 has been mounted in test tray 32 and when pad extender 144 has been moved towards DUT 10 in direction 148.

Following insertion of DUT 10 into test tray 32 and following insertion of plug connector 146 of pad extender 144 into connector 28 of DUT 10, test tray 32 of FIG. 4A may appear as shown in FIG. 4B. Pad extender 144 may contain signal paths that connect pins in connector 28 to corresponding contacts 62 on pad extender 144. Contacts 62 may be configured to mate with corresponding contacts coupled to tester 44 and/or test host 42 during testing in system 30.

Because DUT 10 is connected to test contacts 62 in test tray 32 using pad extender 144 associated with test tray 32, it is not necessary to repeatedly connect and disconnect device under test 10 from cabling at each test station 36. Rather, connections between DUT 10 and the test equipment at each test station 36 by may be formed by coupling contacts 62 in test tray 32 to corresponding contacts (e.g., spring-loaded pins) in each test station 36. By minimizing the number of times that cables need to be connected and disconnected from each device under test, the life of tester cables and connectors may be extended.

The use of test tray 32 and loader 46 may allow DUT 10 to be placed accurately within test stations 36 (e.g., with an accuracy of +/−0.1 mm or better, as an example). Test tray 32 may shield device under test 10 from scratches and other damage during testing. In general, DUT 10 may be received within test tray 32 in either an upwards facing configuration in which display 14 faces outwards away from tray 32 or a downwards facing configuration in which display 14 faces downwards onto base 48 of test tray 32.

FIG. 5A is a perspective view of one suitable embodiment of test tray 32. Tray 32 may be formed using non-marring material such as acetyl plastic, Delrin® (a polyoxymethylene plastic), other plastics, or other suitable non-marring materials. The use of non-marring materials may help avoid scratches or other damage to DUT 10 when DUT 10 is placed within test tray 32. In the example of FIG. 5A, a layer of material 156 may be formed to line the base of recess 154. As an example, material 156 may be formed using the same material that is used to form tray 156. As another example, material 156 may be formed using elastomeric material such as rubberized foam. Material 156 may, in general, be formed using any suitable non-marring material.

Test tray 32 may be provided with guide structures configured to accurately place device under test 10 in a desired location within a recess 154 in tray 32. As shown in FIG. 5A, a guide structure on the end of tray 32 may have an exposed end guide surface such as guide surface 152. Guide structures on the side of tray 32 may have exposed side guide surfaces such as guide surfaces 150.

FIG. 5C is a perspective view of test tray 32 after a device under test has been inserted into test tray 32. As shown in FIG. 5C, test tray 32 may have clamps 164 for holding device under test 10 within test tray 32. The inner surfaces of clamps 164 may serve as guide surfaces 150 (FIG. 5A).

Test tray 32 may also include engagement features such as holes 160 and 162 formed on both ends of tray 32 (see, e.g., top perspective view of tray 32 in FIG. 5A and bottom perspective view of tray 32 in FIG. 5B). Holes such as holes 160 and 162 in test tray 32 or other engagement features may be configured to mate with corresponding engagement features on automated loading equipment such as loaders 46 in test stations 36. For example, holes 160 may be configured to receive corresponding pins from a first robotic arm in loader 46, whereas holes 162 may be configured to receive corresponding pins from a second robotic arm in loader 46. The example of FIGS. 5A, 5B, and 5C in which tray 32 includes eight holes for engaging with automated loading equipment is merely illustrative. If desired, tray 32 may include at least four holes, at least six holes, at least ten holes, etc.

FIG. 6 is a diagram showing how a test station 36 may include loader 46 having multiples arms for interacting with tray 32. As shown in FIG. 6, loader 46 may include a test station loader fixture 200, device under test sensors such as sensors 202 and 203 that are attached to fixture 200, a first movable arm 204-1, and a second movable arm 204-2. Sensor 202 may be a radio-frequency identification (RFID) sensor configured to identify a serial number associated with an incoming tray 32. Based on the identified serial number, test host 42 may be used to determine whether DUT 10 that is mounted within the incoming tray needs to be tested at that test station 36.

Sensor 203 may (as an example) be a laser-based distance sensor that is used to detect whether an incoming tray 32 has been successfully received within arm 204-1. For example, sensor 203 may detect that a tray 32 is being conveyed towards arm 204-1 passing detection plane 203′. If sensor 203 detects that tray 32 has completely moved past sensor detection plane 203′ at a later point in time, DUT 10 has successfully been received within arm 204-1. If sensor 203 detects that tray 32 has not yet completely moved past detection plane 203′, arm 208-1 will remain in a receiving position until DUT 10 is successfully received within arm 204-1.

Loader 46 may have computer-controlled positioners for moving arms 204-1 and 204-2. Arm 204-1 may be moved vertically to pick up test trays. For example, arm 204-1 of may be lowered in direction 300 to pick-up location 302 (i.e., the surface of conveyor belt 38) when it is desired to use arm 204-1 to pick up a new test tray 32 from conveyor belt 38 (see, e.g., FIG. 9). Arm 204-1 may therefore sometimes be referred to as a “pick-up” arm. When it is desired to transfer test tray 32 from pick-up arm 204-1 to arm 204-2, pick-up arm 204-1 may be moved laterally in direction 304.

Arm 204-2 may be positioned in vertical and horizontal alignment with pick-up arm 204-2 to receive test tray 32 from pick-up arm 204-1 (i.e., arm 204-2 may be maintained in a handoff location that is at the same height as pick-up arm 204-1). For testing, arm 204-2 may be moved vertically in direction 306 from the handoff position to testing position 308. When arm 204-2 is in testing position 308, DUT 10 that is mounted in test tray 32 may be tested using test equipment 44 (e.g., a tester for performing optical tests, audio tests, wireless radio-frequency tests, mechanical tests, etc.). Following testing, arm 204-2 may be moved vertically downward in direction 310 until arm 204-2 reaches drop-off position 312 to deposit tray 32 on conveyor belt 38. Arm 204-2 may therefore sometimes be referred to as a “drop-off” arm.

Both pick-up arm 204-1 and drop-off arm 204-2 may be used simultaneously. For example, arm 204-1 may be used in picking up a test tray 32 while arm 204-2 is in the process of dropping off a previous test tray. The simultaneous use of arms 204-1 and 204-2 may help enhance test system throughput.

As shown in FIG. 6, loader 46 may use a screw-based lifting mechanism or other lifting mechanism to vertically lift and lower pick-up arms 204-1 and 204-2. In the example of FIG. 6, loader 46 may have a pick-up arm extender plate such as plate 210-1. Plate 210-1 may have a threaded hole such as hole 214. Computer-controlled motor 222-1 may be used to rotate screw 216-1 about rotational axis 220-1. By rotating screw 216-1, motor 222-1 may be used to raise and lower plate 210-1 and therefore pick-up arm 204-1 in a direction that is parallel to vertical axis Z.

Loader 46 may also be provided with computer-controlled positioners such as positioner 212-1 for moving pick-up arm 204-1 along a direction that is parallel to horizontal axis X. Positioner 212-1 may be a computer-controlled actuator such as a motor-driven or air-driven actuator. Positioner 212-1 may, as an example, be mounted to extender plate 210-1 or other equipment in loader 46.

Similarly, loader 46 may have a drop-off arm extender plate such as plate 210-2. Plate 210-2 may have a threaded hole hole 214. Computer-controlled motor 222-2 may be used to rotate screw 216-2 about rotational axis 220-2. By rotating screw 216-2, motor 222-2 may be used to raise and lower plate 210-2 and therefore drop-off arm 204-2 in a direction that is parallel to vertical axis Z. For example, motor 222-2 may be used to raise plate 210-2 so that DUT 10 that is held by arm 204-2 is raised to test reference plane 230 (i.e., a plane to which a DUT should be vertically aligned so that tester 44 can properly test the DUT).

Loader 46 may also be provided with a positioner such as positioner 212-2 for moving drop-off arm 204-2 along axis X. Positioner 212-2 may be a computer-controlled actuator such as a motor-driven or air-driven actuator. Positioner 212-2 may, as an example, be mounted to extender plate 210-2 or other equipment in loader 46.

Each of arms 204-1 and 204-2 may include an additional contractible member such as arm member 206 and air-driven or motor-driven actuators such as actuators 208. Member 206 of pick-up arm 204-1 may have engagement features such as pins 160′, whereas member 206 of drop-ff arm 204-2 may have engagement features such as pins 162′. Actuators 208 may be used to extend and retract pins 160′ in arm 204-1 and pins 162′ in arm 204-2 in a direction that is parallel to axis Y.

FIG. 7 is a top view of an illustrative conveyor belt 38 in test system 30. Initially, device under test 10 and test tray 32 may be located on the left hand side of conveyor belt 38. Pick-up arm 204-1 may be moved into position 302 (FIG. 9) by a computer following detection of test tray 32 using RFID sensor 202. As conveyor belt 38 moves to the right, DUT 10 and test tray 32 may be received within pick-up arm 204-1. Sensor 203 may be used inform a controlling computer such as host 42 when a test tray is properly received within pick-up arm 204-1.

Holes 160 and 162 in test tray 32 may be configured to engage pins 160′ and 162′, respectively. Initially, pins 160′ may be held in a retracted position by actuators 208. After conveyor belt 38 has moved tray 32 into position within arm 204-1, actuators 208 may be used to extend pins 160′ into holes 160. Once pick-up arm 204-1 has grasped test tray 32 in this way, pick-up arm 204-1 may deliver test tray 32 to tester 44 at the test station associated with pick-up arm 204-1.

FIG. 8 is a cross-sectional end view of pick-up arm 204-1 showing how actuators 208 may insert pins 160′ into holes 160 in test tray 32 so that test tray 32 may be picked up from conveyor belt 38. As with pick-up arm 204-1, drop-off arm 204-2 may be configured to grasp test tray 32 (e.g., using actuator-driven pins 162′ to engage with holes 162 on test tray 32).

FIG. 10 is a flow chart of illustrative steps involved in using loading equipment 46 and test equipment 44 at a test station to perform tests on an incoming DUT. At step 400, a radio-frequency identification (RFID) reader (e.g., sensor 202 in FIG. 6) built into the test station may be used to monitor incoming test trays 32 for RFIDs. Each test tray 32 may contain an RFID tag (e.g., a tag that wirelessly transmits a corresponding tray identifier to RFID reading equipment in system 30). If the RFID reader at the test stations determines that the tray ID for a test tray matches previously received instructions, the test station will initiate pickup arm motions to load the test tray into the test station. Other ways of uniquely identifying each incoming test tray may be used, if desired.

In particular, at step 402, pick-up arm 204-1 may be lowered to position 302 (FIG. 9) adjacent to conveyor belt 38, so that pick-up arm 204-1 can receive test tray 32.

At step 404, light sensors (e.g., sensor 203 of FIG. 6) that are configured to monitor the entrance to arm 204-1 may detect the presence of test tray 32 and may then, as tray 32 moves along conveyor 38, detect the absence of test tray 32. This indicates that tray 32 has entered pick-up arm 204-1, so the pins on pick-up arm 204-1 (i.e., the grabber mechanism formed by pins 160′ and actuators 208 of FIG. 8) may be extended into mating holes 160 in test tray 32 to grab test tray 32 (step 406). Additional light sensors built into arm 204-1 may be used to confirm that test tray 32 has been satisfactorily grabbed by pick-up arm 204-1. Pins 160′ may extend into two or more holes 160 in test tray 32, four or more holes 160 in test tray 32, or any other suitable number of holes 160.

At step 408, pick-up arm 204-1 may be lifted towards the handoff position. At step 410, if drop-off arm 204-2 is busy, system 30 may wait for the previous test tray to be ejected from drop-off arm 204-2. Once drop-off arm 204-2 is free, testing operations may proceed to step 412.

At step 412, lateral actuator 212-1 may be used to move test tray 32 towards arm 204-2. Light sensors associated with pick-up arm 204-1 may confirm when arm 204-1 has extended fully towards drop-off arm 204-2, so that the grabber mechanism (actuators and pins) on drop-off arm 204-2 may grab the test tray (step 414). Drop-off arm 204-2 may also include light sensors that are used to confirm that test tray 32 has been satisfactorily grabbed by arm 204-2.

At step 416, pick-up arm 204-1 may release test tray 32 (e.g., by disengaging pins 160′ from holes 160 in tray 32).

At step 418, pick-up arm 204-1 may be laterally retracted away from drop-off arm 204-2. Lateral retraction of arm 204-1 may be confirmed using light sensors.

At step 420, drop-off arm 204-2 may move test tray 32 to testing position 308 (FIG. 9) and tests on the DUT that is mounted in the grasped test tray 32 may be performed using tester 44.

Following testing of the device under test, drop-off arm 204-2 may be lowered towards the drop-off location on conveyor 38 (step 422). At the drop-off location, test tray 32 may be returned to conveyor belt 38 (e.g., by disengaging pins 162′ from holes 162 in tray 32). As conveyor belt 38 moves, the test tray with the DUT that has been tested may be allowed to pass under pick-up arm 204-1.

The pick-up arm and drop-off arm may be mirrored in software and controlled by separate software objects. Each arm, and thus each arm object, may operate independently, while being controlled by a higher level loader supervisory sequencer. At step 424, drop-off arm 204-2 may return to the hand-off position to await orders from the loader sequencer.

FIG. 11 is a diagram of an illustrative configuration that may be used for test system 30. In the example of FIG. 11, two layers of test stations 36 have been stacked on top of each other. A first conveyor belt 38 may be associated with lower layer 500 of test stations 36 and a second conveyor belt 38 may be associated with upper layer 502 of test stations 36. This is merely illustrative. Space permitting, three or more groups of test stations may be stacked on top of one another, five or more groups of test stations may be stacked on top of one another, etc.

Different types of test stations 36 may be used for performing different types of tests on devices under test 10. For example, stations 36 with open-faced test fixtures may be used for performing optical tests such as ambient light sensor tests and proximity sensor tests. Stations 36 with chambered test fixtures 36 (i.e., stations with test fixtures that are enclosed within metal boxes) may be used for performing wireless signal tests such as antenna tests.

Different types of tests may take different amounts of time to complete. For example, test stations of type A may exhibit an average cycle time of 30 seconds, whereas test stations of type B may exhibit an average cycle time of 45 seconds. To help ensure that devices are not delayed more than necessary when a particular type of test is performed, different number of test stations 36 may be used for performing each type of test. There may be, for example, two test stations 36 on conveyor belt 38 of type A (i.e., for performing tests for a first type of component in device 10) and three test stations 36 on conveyor belt 38 of type B (i.e., for performing tests for a second type of component in device 10). The feed rate in this type of configuration may be 15 seconds. Test data gathered using the different test stations 36 in this way may be fed to associated test host 42 via path 43.

The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention. The foregoing embodiments may be implemented individually or in any combination. 

What is claimed is:
 1. A method for using a test system to test a device under test, wherein the test system includes a conveyor belt, loading equipment, and test equipment, the method comprising: with a first arm in the loading equipment, picking up the device under test from the conveyor belt; handing off the device under test from the first arm to a second arm in the loading equipment; and with the second arm, moving the device under test towards the test equipment so that the device under test is tested using the test equipment.
 2. The method defined in claim 1, wherein the device under test is placed within a test tray, and wherein picking up the device under test comprises picking up the test tray from the conveyor belt with the first arm.
 3. The method defined in claim 1, further comprising: when the test equipment has completed testing the device under test, dropping off the device under test onto the conveyor belt with the second arm.
 4. The method defined in claim 1, wherein the device under test is placed within a test tray having first and second test tray engagement features, wherein the first arm includes first arm engagement features, and wherein picking up the device under test comprises mating the first arm engagement features with the first test tray engagement features to secure the test tray within the first arm.
 5. The method defined in claim 4, wherein the second arm includes second arm engagement features, and wherein handing off the device under test from the first arm to the second arm comprises: while the first arm engagement features are mated with the first test tray engagement features, mating the second arm engagement features with the second test tray engagement features to secure the test tray within the second arm; and while the second arm engagement features are mated with the second test tray engagement features, disengaging the first arm engagement features from the first test tray engagement features.
 6. The method defined in claim 5, wherein the first and second arm engagement features comprises pins, wherein the first and second test tray engagement features comprise holes, wherein mating the first arm engagement features with the first test tray engagement features comprises inserting pins in the first arm into corresponding holes in the test tray, and wherein mating the second arm engagement features with the second test tray engagement features comprises inserting pins in the second arm into corresponding holes in the test tray.
 7. The method defined in claim 1, wherein the loading equipment comprises computer-controlled positioning equipment configured to move the first and second arms along three different axes.
 8. The method defined in claim 1, wherein the loading equipment comprises a screw-based lifting mechanism for raising and lowering the first and second arms with respect to the conveyor belt.
 9. A method for using a test system to test a device under test, wherein the test system includes a conveyor belt, loading equipment, a first sensor, and a second sensor, the method comprising: with the first sensor, detecting an incoming device under test on the conveyor belt; in response to detection of the device under test, lowering a first arm in the loading equipment to receive the incoming device under test; with the second sensor, detecting whether the device under test has been successfully received by the first arm; and in response to detecting that the device under test has been successfully received by the first arm, latching onto the device under test and lifting the device under test from the conveyor belt with the first arm.
 10. The method defined in claim 9, further comprising: transferring the device under test from the first arm to a second arm in the loading equipment.
 11. The method defined in claim 10, wherein test system further includes test equipment, the method further comprising: with the second arm, moving the device under test towards the test equipment so that desired testing can be performed on the device under test using the test equipment.
 12. The method defined in claim 9, wherein the device under test is placed within a test tray having test tray engagement features, wherein the first arm includes arm engagement features, and wherein lowering the first arm to receive the incoming device under test comprises lowering the first arm to a position that allows the arm engagement features of the first arm to mate with the test tray engagement features.
 13. The method defined in claim 9, wherein the device under test is placed within a test tray, wherein the first sensor comprises a radio-frequency identification sensor, and wherein detecting the incoming device under test on the conveyor belt comprises identifying a serial number associated with the test tray with the radio-frequency identification sensor.
 14. The method defined in claim 9, wherein the second sensor comprises a laser-based distance sensor, and wherein detecting whether the device under test has been successfully received by the first arm comprises detecting whether the device under test has been successfully received by the first arm with the laser-based distance sensor.
 15. A test system configured to test a plurality of devices under test, comprising: a first layer of test stations; a first conveyor belt configured to convey devices under test past the test stations in the first layer; a second layer of test stations on top of the first layer of test stations; and a second conveyor belt configured to convey devices under test past the test stations in the second layer.
 16. The test system defined in claim 15, wherein at least one test station in the first layer comprises: test equipment; and loading equipment that is configured to pick-up a device under test in the plurality of devices under test from the first conveyor belt and that is configured to move the device under test towards the test equipment so that the device under test can be tested using the test equipment.
 17. The test system defined in claim 15, wherein at least one test station in the second layer comprises: test equipment; and loading equipment that is configured to pick-up a device under test in the plurality of devices under test from the second conveyor belt and that is configured to move the device under test towards the test equipment so that the device under test can be tested using the test equipment.
 18. The test system defined in claim 15, wherein the plurality of devices under test comprises a plurality of wireless handheld electronic devices under test.
 19. The test system defined in claim 15, wherein each device under test in the plurality of devices under test is mounted within a respective test tray.
 20. The test system defined in claim 15 wherein each test station in the first and second layers comprises: loading equipment having a first arm for latching onto a test tray in which an incoming device under test is mounted and a second arm for receiving the test tray from the first arm; and test equipment configured to test the incoming device under test, wherein the second arm is configured to move the test tray towards the test equipment after receiving the test tray from the first arm. 